Fuel delivery system

ABSTRACT

A fuel delivery system for an engine is provided. The fuel delivery system includes a tank, a temperature sensor, a delivery conduit, a heat exchanger, a control valve, a check valve, a bypass conduit, a bypass valve, and a controller. The controller is configured to receive a signal indicative of a temperature of a fuel present within the tank. The controller is also configured to control the control valve to selectively reverse at least a portion of the fuel in a gaseous state from the heat exchanger to the tank through the bypass conduit based, at least in part, on the received signal. The portion of the fuel is adapted to raise the temperature of the fuel present within the tank.

TECHNICAL FIELD

The present disclosure relates to a fuel delivery system. Moreparticularly, the present disclosure relates to the fuel delivery systemfor an engine.

BACKGROUND

Engines, such as spark ignition engines, compression ignition dual fuelengines, and so on, employ a fuel such as Liquefied Natural Gas (LNG)for combustion. Such engines depend on a pressure within a fuel/LNG tankthereof to provide adequate flow of the fuel in order to eliminate aneed for an additional fuel/cryogenic pump.

During refueling of the LNG tank, a temperature of the LNG tank mayreduce mainly due to low temperature of an incoming supply of the LNG.As a result, a pressure within the LNG tank may be reducedproportionately. Also, during operation of the engine, as the LNG isconsumed, a volume of the LNG within the LNG tank may reduce in turnresulting in a drop in the pressure within the LNG tank. In suchsituations, the pressure of the fuel supplied to the engine may bereduced below a specified threshold resulting in reduced or undesirableperformance of the engine.

U.S. Pat. No. 6,125,637 describes a fuel delivery system having a fueltank configured to receive liquid natural gas. The system includes afirst conduit extending from a vapor holding portion of the fuel tank toan economizer valve. The system includes a second conduit extending froma liquid holding portion of the fuel tank to the economizer valve. Thesystem includes a vaporizer coupled to the economizer valve. Thevaporizer is heated by a coolant from an engine and is positioned belowthe fuel tank. The economizer valve selectively withdraws either liquidnatural gas or vaporized natural gas from the fuel tank depending on apressure within the vapor holding portion of the fuel tank. The systemalso includes a delivery conduit extending from the vaporizer to theengine. The system further includes a return conduit having a checkvalve formed therein extending from the delivery conduit to the vaporholding portion of the fuel tank for pressurizing the fuel tank.

SUMMARY OF THE DISCLOSURE

An aspect of the present disclosure provides a fuel delivery system foran engine. The fuel delivery system includes a tank adapted to store afuel. The fuel delivery system includes a temperature sensor provided inassociation with the tank. The temperature sensor is configured togenerate a signal indicative of a temperature of the fuel present withinthe tank. The fuel delivery system includes a delivery conduit coupledto the tank and the engine. The fuel delivery system includes a heatexchanger coupled to the delivery conduit downstream of the tank. Theheat exchanger is adapted to convert the fuel from a liquid state to agaseous state. The fuel delivery system includes a control valve coupledto the delivery conduit downstream of the heat exchanger. The controlvalve is adapted to control a flow of the fuel from the heat exchangerto the engine. The fuel delivery system includes a check valve coupledto the delivery conduit downstream of the tank and upstream of the heatexchanger. The fuel delivery system includes a bypass conduit coupled tothe delivery conduit and parallel to the check valve. The fuel deliverysystem also includes a bypass valve coupled to the bypass conduit. Thefuel delivery system further includes a controller coupled to thetemperature sensor and the control valve. The controller is configuredto receive the signal indicative of the temperature of the fuel presentwithin the tank. The controller is also configured to control thecontrol valve to selectively reverse at least a portion of the fuel inthe gaseous state from the heat exchanger to the tank through the bypassconduit based, at least in part, on the received signal. The portion ofthe fuel is adapted to raise the temperature of the fuel present withinthe tank.

Other features and aspects of this disclosure will be apparent from thefollowing description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary engine, according to oneembodiment of the present disclosure

FIG. 2 is a schematic representation of a fuel delivery system for theengine of FIG. 1, according to one embodiment of the present disclosure;and

FIG. 3 is a flowchart of a method of working of the fuel delivery systemof FIG. 2, according to one embodiment of the present disclosure.

DETAILED DESCRIPTION

Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or the like parts. Referring to FIG.1, an exemplary engine 10 is illustrated. The engine 10 is an internalcombustion engine powered by one or more fuels. In one embodiment, theengine 10 may be a spark ignition engine powered by Liquefied NaturalGas (LNG).

In another embodiment, the engine 10 may be a compression ignition dualfuel engine powered by a combination of LNG and diesel, such as in aDynamic Gas Blending (DGB) engine. The engine 10 may be used forapplications including, but not limited to, power generation,transportation, construction, agriculture, forestry, aviation, marine,material handling, and waste management.

The engine 10 includes an engine block 12. The engine block 12 includesone or more cylinders (not shown) provided therein. The cylinders may bearranged in any configuration such as inline, radial, “V”, and so on.The engine 10 also includes a cylinder head 14 mounted on the engineblock 12. The cylinder head 14 houses one or more components and/orsystems (not shown) of the engine 10 such as a valve train, an intakemanifold, an exhaust manifold, sensors, and so on. Additionally, theengine 10 may include various other components and/or systems (notshown) such as a crankcase, a lubrication system, an air system, acooling system, a turbocharger, an exhaust gas recirculation system, anexhaust gas aftertreatment system, other peripheries, and so on.

Referring to FIG. 2, the engine 10 includes a fuel delivery system 16.The fuel delivery system 16 includes a tank 18. The tank 18 is adaptedto store the LNG fuel hereinafter referred to as “the fuel”. The tank 18may be any tank known in the art adapted for cryogenic applications. Assuch, the tank 18 may include an insulation thereon for limiting heattransfer between the fuel therein and atmosphere.

The fuel delivery system 16 includes a delivery conduit 20. The deliveryconduit 20 is coupled to the tank 18 and the engine 10. The deliveryconduit 20 is adapted to provide a flow of the fuel from the tank 18 tothe cylinders of the engine 10. The fuel delivery system 16 alsoincludes a temperature sensor 22 provided in association with the tank18.

In the illustrated embodiment, the temperature sensor 22 is coupled tothe delivery conduit 20 adjacent to the tank 18. In other embodiments,the temperature sensor 22 may be coupled to the tank 18. The temperaturesensor 22 is configured to generate a signal indicative of a temperatureof the fuel present within the tank 18. The temperature sensor 22 may beany temperature sensor known in the art adapted for cryogenicapplications.

The fuel delivery system 16 includes a heat exchanger 24 also known as avaporizer. The heat exchanger 24 is coupled to the delivery conduit 20.More specifically, the heat exchanger 24 is provided downstream of thetank 18 and upstream of the engine 10. The heat exchanger 24 is adaptedto receive the fuel from the tank 18 and convert the fuel from a liquidstate to a gaseous state. More specifically, the heat exchanger 24 isadapted to receive the LNG from the tank 18 and convert the LNG tovaporized natural gas.

The heat exchanger 24 may be any heat exchanger known in the art adaptedfor cryogenic applications. In one embodiment, the heat exchanger 24 maybe an ambient air-to-liquid type of heat exchanger adapted to transferheat between ambient air and the fuel. In another embodiment, the heatexchanger 24 may be a liquid-to-liquid type of heat exchanger adapted totransfer heat between a fluid and the fuel. The fluid may be a heatedengine coolant, engine oil, hydraulic oil, and so on.

The fuel delivery system 16 includes a control valve 26 coupled to thedelivery conduit 20. More specifically, the control valve 26 is provideddownstream of the heat exchanger 24 and upstream of the engine 10. Thecontrol valve 26 is adapted to control a flow of the fuel/vaporizednatural gas from the heat exchanger 24 to the engine 10. The controlvalve 26 may be any valve known in the art adapted for controlling flowof gaseous fluids.

Additionally, the fuel delivery system 16 includes a check valve 28coupled to the delivery conduit 20. The check valve 28 is provideddownstream of the tank 18 and upstream of the heat exchanger 24. Thecheck valve 28 is adapted to control a reverse flow of thefuel/vaporized natural gas from the heat exchanger 24 towards the tank18. The check valve 28 may be any check valve known in the art adaptedfor cryogenic applications.

The fuel delivery system 16 includes a bypass conduit 30. The bypassconduit 30 is coupled to the delivery conduit 20 and in parallel withrespect to the check valve 28. More specifically, a first end 32 of thebypass conduit 30 is coupled to the delivery conduit 20 downstream ofthe check valve 28 and upstream of the heat exchanger 24. Also, a secondend 34 of the bypass conduit 30 is coupled to the delivery conduit 20downstream of the tank 18 and upstream of the check valve 28.

The fuel delivery system 16 also includes a bypass valve 36 coupled tothe bypass conduit 30. The bypass valve 36 may be any valve known in theart adapted for controlling flow of gaseous fluids. In one embodiment,the bypass valve 36 may be any check valve known in the art adapted tocontrol a reverse flow of a fluid therethrough. In another embodiment,the bypass valve 36 may be any pressure regulated valve known in the artadapted to operate at a predetermined pressure value. The bypass conduit30 and the bypass valve 36 will be explained in more detail later.

The fuel delivery system 16 further includes a controller 38. Thecontroller 38 is coupled to the temperature sensor 22 and the controlvalve 26. The controller 38 is configured to receive the signalindicative of the temperature of the fuel present within the tank 18from the temperature sensor 22.

The controller 38 is also coupled to an engine parameter sensor (notshown) associated with the engine 10. The engine parameter sensor isconfigured to generate a signal indicative of an engine operatingparameter. The engine operating parameter may be any engine operatingcondition such as a fuel command, a throttle command, and so on, and mayvary based on application requirements. In other embodiments, thecontroller 38 may receive the signal indicative of the engine operatingparameter from an Engine Control Module (ECM) (not shown) associatedwith the engine 10.

Accordingly, the controller 38 is configured to receive the signalindicative of the engine operating parameter. Based on the receivedsignal indicative of the engine operating parameter, the controller 38is configured to determine an appropriate time period/duration toselectively reverse at least a portion of the fuel in the gaseous statefrom the heat exchanger 24 to the tank 18 through the bypass conduit 30.As such, it may be desirable to bypass the portion of the fuel underspecific engine operating conditions in order to ensure a demand of theengine 10 is met.

The controller 38 is also configured to control the control valve 26 toselectively reverse at least the portion of the fuel in the gaseousstate from the heat exchanger 24 to the tank 18 through the bypassconduit 30 based, at least in part, on the received signal. Morespecifically, the controller 38 is configured to control the controlvalve 26 to selectively reverse a flow of the portion of the vaporizednatural gas to the tank 18 from the heat exchanger 24 through the bypassconduit 30 and the bypass valve 36 based on the signals received fromthe temperature sensor 22. The portion of the fuel/vaporised natural gasis adapted to raise the temperature of the fuel present within the tank18.

During operation of the fuel delivery system 16, the controller 38receives the signal indicative of the temperature of the fuel presentwithin the tank 18 from the temperature sensor 22. Based on the receivedsignal, the controller 38 determines a pressure within the tank 18. Thecontroller 38 may determine the pressure within the tank 18 based on acorrelation. The correlation may be stored in a memory (not shown) ofthe controller 38 or a database (not shown) coupled to the controller38.

In one situation, the correlation may be a dataset. The dataset mayinclude various values of the pressure within the tank 18 for differentvalues of the temperature of the fuel present within the tank 18. Inanother situation, the correlation may be a mathematical expressionbetween the temperature of the fuel within the tank 18 and the pressurewithin the tank 18. Accordingly, the controller 38 may look up thedataset or refer the mathematical expression in order to determine thepressure within the tank 18 based on the temperature of the fuel presentwithin the tank 18.

In a situation when the temperature of the fuel present within the tank18 may drop below a threshold temperature, the controller 38 controlsthe control valve 26 to reverse the flow of the portion of the vaporizednatural gas to the tank 18. The threshold temperature may be such thatthe pressure within the tank 18 at the threshold temperature may beapproximately equal or exceed a boost pressure of the engine 10.

More specifically, the controller 38 closes the control valve 26partially or completely, based on application requirements which mayalso include the signal indicative of the engine operating parameter, inorder to increase a backpressure downstream of the control valve 26 upto the check valve 28. The backpressure results in a pressure spikedownstream of the heat exchanger 24 and reversal of the portion orcomplete flow of the vaporized natural gas through the bypass conduit 30and the bypass valve 36 to the tank 18.

The bypassed and reversed flow of the vaporized natural gas is bubbledand mixed with the fuel/LNG present within the tank 18. Due to heattransfer between the vaporized natural gas and the fuel present withinthe tank 18, the temperature of the fuel present within the tank 18increases gradually. As a result, the pressure within the tank 18increases proportionately. As the temperature of the fuel present withinthe tank 18 may be approximately equal or higher than the thresholdtemperature, the controller 38 is adapted to control the control valve26 to terminate the reverse flow of the vaporised natural gas to thetank 18.

More specifically, the controller 38 opens the control valve 26partially or completely, based on application requirements which mayalso include the signal indicative of the engine operating parameter, toprovide the flow of the vaporized natural gas further to the engine 10.As a result, the backpressure downstream of the control valve 26/heatexchanger 24 is reduced, in turn reducing or terminating the reversal ofthe portion or complete flow of the vaporized natural gas respectivelythrough the bypass conduit 30 to the tank 18.

The fuel delivery system 16 also includes an Excess Flow (EF) valve 40coupled to the delivery conduit 20. The EF valve 40 is provideddownstream of the check valve 28 and upstream of the heat exchanger 24.The EF valve 40 is adapted to control a flow rate of the fuel from thetank 18 towards the heat exchanger 24. The fuel delivery system 16further includes a Shut-Off (SO) valve 42 coupled to the deliveryconduit 20. The SO valve 42 is provided downstream of the check valve 28and upstream of the heat exchanger 24. More specifically, the SO valve42 is provided downstream of the EF valve 40 and upstream of the heatexchanger 24. The SO valve 42 is adapted to manually control the flow ofthe fuel from the tank 18 towards the heat exchanger 24.

The EF valve 40 and/or the SO valve 42 may be any valve known in the artadapted for respective cryogenic applications. It should be noted that anumber, configuration, and/or layout of the EF valve 40 and/or the SOvalve 42 described herein is merely exemplary. Based on applicationrequirements, the fuel delivery system 16 may omit components describedherein and/or may include additional components without limiting thescope of the disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure relates to the fuel delivery system 16. Referringto FIG. 3, a method 44 of working of the fuel delivery system 16 isillustrated. At step 46, the controller 38 receives the signalindicative of the temperature of the fuel present within the tank 18from the temperature sensor 22. At step 48, the controller 38 controlsthe control valve 26 to selectively reverse the flow of the portion ofthe fuel in the gaseous state from the heat exchanger 24 to the tank 18through the bypass conduit 30 and the bypass valve 36 based, at least inpart, on the received signal. The portion of the fuel is adapted toraise the temperature of the fuel present within the tank 18.

The fuel delivery system 16 provides a simple, effective, and costefficient method for controlling the pressure within the tank 18 and, inturn, the pressure of the vaporized natural gas provided to the engine10. The fuel delivery system 16 eliminates need for an additionalboost/pressure pump, thus, lowering system cost and complexity. The fueldelivery system 16 may be incorporated in other engines with minormodification to the existing fuel system.

While aspects of the present disclosure have been particularly shown anddescribed with reference to the embodiments above, it will be understoodby those skilled in the art that various additional embodiments may becontemplated by the modification of the disclosed machines, systems andmethods without departing from the spirit and scope of the disclosure.Such embodiments should be understood to fall within the scope of thepresent disclosure as determined based upon the claims and anyequivalents thereof.

What is claimed is:
 1. A fuel delivery system for an engine, the fueldelivery system comprising: a tank adapted to store a fuel; atemperature sensor provided in association with the tank, thetemperature sensor configured to generate a signal indicative of atemperature of the fuel present within the tank; a delivery conduitcoupled to the tank and the engine; a heat exchanger coupled to thedelivery conduit downstream of the tank, the heat exchanger adapted toconvert the fuel from a liquid state to a gaseous state; a control valvecoupled to the delivery conduit downstream of the heat exchanger, thecontrol valve adapted to control a flow of the fuel from the heatexchanger to the engine; a check valve coupled to the delivery conduitdownstream of the tank and upstream of the heat exchanger; a bypassconduit coupled to the delivery conduit and parallel to the check valve;a bypass valve coupled to the bypass conduit; and a controller coupledto the temperature sensor and the control valve, the controllerconfigured to: receive the signal indicative of the temperature of thefuel present within the tank; and control the control valve toselectively reverse at least a portion of the fuel in the gaseous statefrom the heat exchanger to the tank through the bypass conduit based, atleast in part, on the received signal, wherein the portion of the fuelis adapted to raise the temperature of the fuel present within the tank.2. The fuel delivery system of claim 1, wherein the controller isfurther configured to receive a signal indicative of an engine operatingparameter from at least one of an engine parameter sensor and an EngineControl Module (ECM) associated with the engine.
 3. The fuel deliverysystem of claim 2, wherein the engine operating parameter includes afuel command.
 4. The fuel delivery system of claim 1, wherein the fuelis Liquefied Natural Gas (LNG).
 5. The fuel delivery system of claim 1,wherein the bypass valve is any one of a check valve and a pressureregulated valve.
 6. The fuel delivery system of claim 1 further includesan Excess Flow (EF) valve coupled to the delivery conduit downstream ofthe check valve and upstream of the heat exchanger.
 7. The fuel deliverysystem of claim 1 further includes a Shut-Off (SO) valve coupled to thedelivery conduit downstream of the check valve and upstream of the heatexchanger.